1. Field of the Invention
The present invention relates to a penile prosthesis for erecting a male penis, and methods of implanting the same.
2. Description of Related Art
A penile prosthesis is typically installed in a patient to remedy erectile impotence. One common type of penile prosthesis, termed an inflatable penile prosthesis or IPP, is provided with three separate functional elements, namely a single cylinder or more commonly a pair of inflatable cylinders for insertion into the corpus cavernosa regions of the penis, a reservoir for disposition in the abdominal cavity and a pump for disposition in the scrotum, together with tubing which is trimmed to length and used to interconnect all of the elements at the time of surgery. Specifically, there is typically one tube for connection from the pump to each cylinder and one tube for connection from the pump to the reservoir. In operation after implantation, the cylinders are filled with a fluid from the reservoir that inflates the cylinders, thereby causing the penis to erect. When fluid is drained from the cylinders back to the reservoir, the cylinders and penis return to a relaxed position (flacid state). For inflation of the cylinders, the pump is manually activated to add fluid from the reservoir to the cylinders, with a valve being provided with the pump to permit and restrict the flow of fluid to and from the cylinders. Such devices are described in various prior art references such as U.S. Pat. Nos. 3,855,122, 3,954,102, 4,009,711, 4,201,202, 4,235,227 and 4,318,396. (The foregoing types of prostheses are commonly referred to as "three piece" penile prostheses, which terminology is preserved in the description of the present invention to distinguish over "two piece" penile prostheses wherein the pump also functions as the reservoir, though as shall be seen, the present invention does not have separate "pieces" but rather is one integrated assembly requiring no further interconnection at the time of implantation, in a preferred embodiment, a partially prefilled assembly substantially free of air and ready for implantation and final filling.)
The reservoir is usually a flexible bag for volume expansion and contraction primarily through shape changes as opposed to material stretching. For one method of implantation, the reservoir is typically inserted through the inguinal ring and implanted into the abdominal cavity behind the muscles of the lower abdomen of the patient. In that regard, the reservoir is generally too large to be pushed through the inguinal ring if it is filled with the intended working fluid, so the reservoir is usually substantially deflated before implantation.
Present surgical procedures include implanting the cylinders in the penis and filling them to test the resultant erection, and then emptying the cylinders, implanting an empty or substantially empty reservoir into the pelvic cavity, filling the reservoir with the filling fluid, implanting the pump and then connecting all of the elements together with the tubing. In connecting the tubing from the reservoir to the pump, an extra long length of tubing is generally supplied. The tubing must be clamped off and trimmed to the proper length for the individual patient. The pump is then implanted into the scrotum and the cylinders are inserted into the penis pendulum.
As indicated above, the reservoir must be devoid of most fluid in order to be implanted through the inguinal ring, and the pump, cylinders and tubing do not have sufficient volume to retain all of the fluid needed in the system. Therefore, the prior art inflatable penile implant systems must remain unconnected, and are typically unfilled until after the reservoir is installed. This is because a filled reservoir, if first connected, cannot be sufficiently temporarily drained into the remaining components for implantation into a patient. Thus, in order to properly install a prior art IPP of this type, it is necessary to first trim the tubing to length and fill the reservoir to purge most air therefrom, then to substantially empty the reservoir and clamp the tubing without reintroducing air, then to pass the reservoir through the inguinal ring and into the abdominal cavity, and then to fill the reservoir through the unconnected tubing before the remainder of the device is installed and connected together. The air purging, etc. of the reservoir prior to its implantation and its refilling after implantation in the abdominal cavity is time consuming, thereby not only increasing implantation time, but also the cost and risk associated with implantation.
Another problem with prior art penile implants of this type is that the attachment of the pump and cylinder to the reservoir often traps air within the system. Excessive air is undesirable because it is compressible, will leak through a valve at a much higher rate than the intended fluid and has other undesirable effects such as possibly creating noise when being pumped with the fluid. Air also usually is present in lieu of an approximately equal amount of additional working fluid, thereby reducing the total amount of the working fluid present, potentially below the minimum required for proper operation of the system. Since the air will slowly disperse by osmosis through the implant wall over a period of time, an implant that works satisfactorily immediately after implantation on the combination of the intended working fluid and air functioning for the time being as additional working fluid may not work properly after a period of time. Thus the presence of air should be minimized. To purge the assembled prosthesis of air, a small volume of fluid is added to the system. The surgeon must then wait while the trapped air separates from the fluid. A needle is then inserted into the pocket of air and the air is withdrawn from the system. This procedure is repeated until all visible air is removed. The pump is then implanted into the scrotum and the cylinder is inserted into the penis pendulum. The assembly of the prosthesis and the subsequent purging of air are also time consuming steps that extend the length of surgery. Additionally, with the prior art methods, it is difficult to insure that all of the air is removed from the prosthesis assembly as desired.
The interconnection of the components of the prior art penile implants is also problematic. (Connectors such as those described in U.S. Pat. Nos. 4,537,183 have been used in the past for this purpose.) The tubes must connect the components together as described above, but this interconnection is time consuming and labor intensive, thereby also increasing the time required for the operation and the associated risks of extending the time of the operation. Further, the connectors present a step change from the flexibility of the tubes, creating stress concentrations at the point of attachment of the tubes to the connectors and providing a possible source of failure over a period of time because of repeated flexing at these points. Elimination of the connectors would eliminate this potential source of failure, as a length of flexible tubing integral with the same adjacent tubing is itself extremely reliable.
In U.S. Pat. Nos. 4,597,765, a method and apparatus for packaging a fluid filled prosthesis is disclosed which allows the prefilling of a prosthesis at the factory and shipment and storage of the prosthesis in the fluid filled state, despite the tendency for fluid migration through the walls of the device, by establishing mass transfer equilibrium within the package. The method disclosed works well for two piece penile prostheses, particularly those adversely effected by slight fluid loss, but is not applicable to three piece prostheses, as the reservoir of a prefilled three piece prosthesis generally cannot be adequately collapsed for implantation purposes.
It would therefore be desirable to have a penile prosthesis and a method of installing the same that would make it easier and faster to implant, and which would eliminate the connectors and thus a potential source of deterioration and failure in the operating system, thereby greatly reducing surgery time and failure after some period of use, to the advantage of the patient and surgeon alike.